A work machine utilizes a drivetrain to transmit power from an engine to a set of wheels. In the drivetrain, a clutch transmits engine power to a transmission, and the transmission transmits power to a final drive. The final drive comprises a differential gearset, planetary gearset a differential housing, and an axle housing. An input shaft transmits power from the differential gearset to the planetary gearset, and an output shaft transmits power from the planetary gearset to the set of wheels. A lubricant is contained within the axle and differential housings, and thus, the planetary gearset and the differential gearset operate in conjunction with the lubricant.
In the planetary gearset, there is a sun gear, a ring gear, a carrier, pins, and planet gears. The sun gear, which is the center of the planetary gearset, may be formed into the input shaft, or it may be splined onto the input shaft. The planet gears and the carrier rotate about the sun gear. The planet gears are meshed between the ring gear and the sun gear, and the planet gears turn on their own pins around the sun gear. The pins are engaged with the carrier to ensure that the planet gears are equally spaced. The carrier may be connected to the output shaft.
The final drive further comprises a brake assembly. In the brake assembly, there is a friction disc splined to the input shaft. To prevent rotation of the friction disc and input shaft, a piston, a piston plate, and a reaction plate sandwich the friction disc. The friction disc has grooves on each of its sides to facilitate the flow of the lubricant.
When the planetary gearset and friction disc rotate at a high speed, they cause the lubricant to rotate. As the lubricant rotates, centrifugal forces cause it to travel in a radial direction away from the rotational axis of the input shaft. Accordingly, the lubricant travels in a rotational direction and in a radial direction, and this causes the lubricant to travel about the inner surfaces of the differential and axle housings in the form of a lubricant ring. Under these circumstances, the lubricant may not cover the entire friction disc. Accordingly, there is a need for a final drive comprising a lubrication system to provide sufficient lubricant to the brake assembly. Such a system increases the brake's energy density capability and improves the brake assembly's durability characteristics.